What is the formula used to calculate impedance in an electrical circuit?

The formula for calculating impedance in an electrical circuit combines both resistance and reactance. Impedance is a complex quantity that accounts for the opposition to alternating current (AC) flow in a circuit, represented as Z. The components are resistance (R) and reactance (X), with the latter often being characterized by either inductive reactance (Xl) or capacitive reactance (Xc).

The correct formula, which is represented in the answer provided, is the square root of (R^2 + Xl^2). This captures the relationship that resistance and inductance create a combined effect that changes how current behaves in an AC circuit. The squared values of R and Xl reflect the Pythagorean theorem, which is fundamental when dealing with perpendicular components in a right triangle—R being one leg and Xl being the other. The resulting impedance (Z) then serves as the hypotenuse, indicating the total opposition to the flow of current in the circuit.

This insight is critical for linemen and electrical professionals, as it allows them to determine how circuits will perform under alternating current, facilitating voltage drops, phase relationships, and energy loss calculations.

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